Transmission warning

The transmission has reported a fault or has exceeded its safe temperature. Many automatic gearboxes respond by locking into a single gear or refusing to shift — often called limp mode — specifically to protect themselves while you get somewhere safe.

• Overheating after towing, heavy loads or long periods in slow traffic
• Low or degraded transmission fluid
• A solenoid, speed sensor or selector fault
• Clutch wear in a dual-clutch gearbox
• A control software fault

Ease off and reduce the load on the gearbox. If the car has dropped into limp mode, drive gently to somewhere safe and stop; a heat-related warning will sometimes clear after the transmission has cooled.

Do not continue towing, climbing or pressing on with the light showing. Heat is what destroys gearboxes, and the warning exists because the temperature is already above where it should be.

Promptly, and certainly before any long journey. Transmission faults left to develop very rarely stay small ones.